M101 in Ursa Major is a beautiful, large, face-on spiral galaxy
of the type Sc, meaning it has extended spiral arms and a very small central
bulge. Like in other large nearby spiral galaxies, several knots of emission
nebulosity can be recorded on deep photographs. The galaxy is quite near, at a
distance of only 18 million lightyears, and is the center of a small group of
galaxies with 23 known members, mostly dwarf galaxies. This is a neighbor group
to the Local Group of galaxies, of which our Milkyway Galaxy is a member.
M101, Wide Field, the full frame of this photograph.
- Instrument: 9.5" f/4.9 Newtonian
- F/stop: 5.6
- Exposure: 12 x 10 minutes + 2 x 2 minutes
- Camera: Canon 350D with Baader UV-IR-Cut-Filter
- Sensitivity: ISO 800
- Date: May 30, 2008 / April 12, 2009 / May 24, 2009
- Exposure start: 23:43 MESZ / 22:40 MESZ / 1:32 MESZ
- Location: Ebenwaldhöhe, Lower Austria / Ebenwaldhöhe, Lower Austria / Oberleiserberg, Lower Austria
- Conditions: Visual limiting magnitude 6.0 mag, seeing 2.8" FWHM, temperature 18.5°C, slight wind, no dew / Visual limiting magnitude 5.8 mag, seeing 3-4" FWHM, temperature 6°C, slight wind, no dew / Visual limiting magnitude 6.0 mag, seeing 2" FWHM, temperature 11.5°C, no wind, no dew
- Autoguider: Meade Pictor 216 XT, max. error: 3" (RA) / 2" (Dec); 1" (RA) / 1" (Dec); 1" (RA) / 1" (Dec)
- Enhancement: Basic data reduction, combine, logarithmic curves, background flattening, color correction, noise filtering, star size reduction, dynamic range extension, local contrast enhancement
- Remarks: It has been a long hunt for exposures of this galaxy. During all three nights the exposure series were cut short by incoming clouds.
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